Asymptotic expansion of high order (see [1]}) :
\(\forall \lambda >0,\quad \mbox{ }I_{\nu }(\lambda )\underset{\nu \rightarrow \infty }{\sim }\frac{1}{\sqrt{2\pi \nu }}\left(\frac{e\lambda }{2\nu }\right)^{\nu }\quad \mbox{ and }\quad K_{\nu }(\lambda )\underset{\nu \rightarrow \infty }{\sim }\sqrt{\frac{\pi }{2\nu }}\left(\frac{e\lambda }{2\nu }\right)^{-\nu }.\) 
